The present invention relates to new sparingly soluble salts of aminoglycoside antibiotics.
Aminoglycoside antibiotics such as gentamycin or tobramycin are usually employed in the form of their sulfates, which are readily soluble in water. The antibiotics are rapidly released from these salts and distribute themselves around the body. In some cases, this property is a disadvantage, in particular if a locally limited infection is to be combatted, for example an infected bone. In these cases, more sparingly soluble salts, from which the antibiotic is released more slowly and which therefore can display a certain depot action, are desirable.
Some sparingly soluble salts of aminoglycoside antibiotics are known. Thus, for example, U.S. Pat. No. 3,091,572 mentions various sparingly soluble salts of gentamycin (for example, salts of fatty acids containing 8 or more C atoms, e.g., lauric acid, stearic acid, palmitic acid or oleic acid; aralkanoic acids, e.g., phenylbutyric acid; arylcarboxylic acids, e.g., naphthalene-1-carboxylic acid; and sulfuric and sulfonic acids, e.g., laurylsulfuric acid and dodecylbenzenesulfonic acid).
It has been found that these salts display certain disadvantages when used For example, they have a waxy, clearly hydrophobic nature which impedes their galenical processing.